Manufacture of compound tubes.



No. 66l,l08. Patented Nov. 6, I900.

A. SCHMITZ.

MANUFACTURE OF COMPOUND TUBES.

(Application filed. Dec. 4, 1899.)

(No Model.)

Jimmy.

UNITED STATES PATENT ()FFICE.

ALliER'l. SCHMITZ, F RAUNHEIllI-ON-THE-MAIN, GER-MANY.

MANUFACTURE OF COMPOUND TUBES.

SPECIFICATION forming part of Letters Patent No. 661,108, dated November 6, 1900.

Application filed December 4, 1899. Serial No. 739,175. (No model.)

To allwh/mt it nuty concern:

Be it known that I, ALBERT SUHMITZ, a citizcn of the Grand Duchy of Hesse, and a resident of Frankfurterstrasse 50, Raunheim onthe-Main, in the Grand Duchy of Hesse, Ger-- man Empire, have invented certain new and useful Improvements in the Manufacture of pipes the walls of which are composed of several layers of sheet metal, which are welded together, so as to form one solid body.

In the accompanying drawings the process is shown in its different stages.

Figure 1 shows a strip of sheet metal out of v\'hi'ch the pipe is formed. Fig; 2 shows the drawing of said strip'th rough a drawinghole and the formation of the pipe. Fig.3 showsthe thus-formed pipe placed on a second strip of sheet metal, and Fig. 4Sh0WS both passed through a second drawing-hole. Fig. 5 is a cross-section through the pipe formed by this process. I

Y A strip a of sheet-iron is drawn through a drawing-hole b, and thereby a tube 0 is formed.

This tube is placed upon a second strip d of sheet-iron, &c., and drawn through a second drawrhole e, whereby this second strip also forms a pipe f, surrounding closely the first one. In selecting proper dimensions for the strips and the drawing-holes a pipe with double walls is formed, which are intimately pressed together. The same process may be further repealed, thereby strengthening the walls of the pipes by further thicknesses of metal. The drawing-holes are cone-shaped, and the walls are thickest at their apex or smallest end and taper to a fine edge at their opposite end, as shown by the dotted lines in it receives its greatest strain.

Figs. 2 and 4, so that when the plate is in- I sorted at the largest end it will readily bend and encircle the inner wall of the apex of the same. Thus it will be seen that the wall of the d rawing-hole is thickest at the point where In placing the pipe 0 on the second strip dcare must be taken to so place it that its seam will not coincide with the seam formed by the edges of the second. strip (7.

The strip a maybe heated to a welding heat before passing it through the drawinghole Z). Then its rims will be welded together after leaving the same; but the drawing may also take place in red heat or in cold- Then of course no welding takes place. The second strip (1 of sheet metal also may be heated either to the welding tem perat u re or only to red heat, or it may even lie-left cold. In case the welding does not take place in the first operation the ready-formed pipe is ultimatel y brought to tho weldi ng heat and passed through a d rawing-hole of proper dimensions or through rollers, thereby welding the whole together.

What I claim is The process of making compound tubes which consists in forming a tube from a flat skelp, placing the tube so formed upon an- -other fiat skelp and drawing said tube and skelp simultaneously through a die whereby the second skelp is fm'llluil into a tube around the first-named tube, with their joints out of aline'ment, substantially as described.

In testimony whereof I ai'lix my signature in presence of two witnesses.

ALBERT SGHMITZ.

\Vi tn esses:

WoLnEMAn iinurr, lies or ilAsrEn. 

